I’ve often wondered just how certain animals can stomach certain things.
Taste buds play an important function in letting an animal know what is good or bad to eat. If you get right down to it, this can mean the difference between life or death; toxins or harmful substances will be detected by the buds, the body responds by deeming that food as not good to eat, and it will be avoided. Tasting accurately is therefore a matter of survival
At Londolozi, seeing a hyena gnawing away at week-old carrion, and more especially smelling that carrion yourself, can be enough to make your stomach turn. Yet out in the wilds, it can appear that – at least for the most part – the animals are rather indiscriminate in their taste selections. This is not the case however, and one needs to look at the animal’s lifestyle, diet and tongue structure in order to get a better appreciation of how things may taste to certain creatures, and why hyenas don’t gag when stuffing themselves on rotting hippo.
Carnivores are the obvious group to start with, as many of the things they eat might seem quite disgusting to us. When one examines their tongues, however, you find a marked difference between the density of their taste buds compared to ours. Humans have on average around 10 000 buds, whereas most carnivores have less than 500. That’s a ratio of 20:1.
Looking at exactly what the carnivores can and can’t taste, we find that they are receptive to bitter flavours, but can’t taste sweet things. This is because sugars aren’t part of their diet, so it is unnecessary for them to be able to detect them. Bitterness however, is important, as it can be the difference between truly rancid meat and meat that is still okay to eat. Obviously the definition of what constitutes rancid meat is slightly different for a male lion than it is for a human, but here we have to look at the carnivore’s digestive system as well. A digestive tract that is far more able to process meats and can handle bacteria that would give a person immediate and acute gastrointestinal problems has a far higher tolerance for meats that we would consider inedible.
The simple fact that carnivores’ diets consist of almost exclusively one type of food – meat – means that extra taste buds would simply be wasted. The herbivore’s need to detect toxins that would be in plants is not needed by carnivores, as unless they’re eating something like a Poison Arrow Frog, the meat they are consuming will be toxin-free.
Herbivores are at the other end of the spectrum, having far more taste buds than humans; more than double in some cases, with cows being in possession of around 25000. Although this seems contradictory, given that herbivores don’t eat a wide variety of food, and logic might dictate that they should therefore also have few buds, they actually need to be extremely sensitive about what they put in their mouths. Bulk grazers in particular who can munch away at whatever’s in front of them need to be able to distinguish the bitter tastes of dangerous plants that might be concealed amidst safe vegetation, as they might not be looking carefully at their food source. Sensitivity to toxins is crucial, as the plant world is full of chemical defences.
Sweet and salty do feature in the tastes of herbivores tastes as well, as plants containing different amounts of minerals need to be analysed and favoured depending on the animal’s immediate needs and electrolyte balance.
Catfish are the world champs of tasting, having about 175 000 buds; they often live in murky-water environments and sight will play almost no role in food detection. Ironically, despite having the most sensitive taste out there, catfish are some of the least tastiest of their family!
In the wild, where animals rarely have the luxury of the choice of food that many humans do, the preference for a certain item will almost always come second behind the necessity of eating when something’s actually available. If it’s in front of you and you can stomach it, eat it!
I guess I’m just grateful that tonight for dinner I’ll be able to opt for something that I like, as opposed to the hyena that I saw this morning, his head down to the ground, sniffing along and hoping to come across any kind of carrion he could find, be it fresh or over a week old. As to the question of whether carnivores are able to like something they’re eating, that’s a discussion for another day.